The tires can handle a lot of pressure. The rating stamped on the tire is perfectly safe. If even 0.1% couldn't handle that pressure, the tire makers would be facing hundreds or thousands of lawsuits. So they overbuild them on purpose.

I've read a few times that tires are burst tested to ~200 psi. Not that you want to drive around at that because bumps might be an issue, but they can handle a lot more than we give them credit for. I know at least a few people who have ran around at 70 psi in their tires...

I know several racers who will race on conventional V, Z, and ZR-rated tires at up to 90psi. While I wouldn't recommend that on city streets, it does make me a little more comfortable going a few psi over the sidewall max.

I periodically thought my tires looked low, as radials tend to, with my first car, around 2,001. I did not have a tire gauge and the gas stations that I used did not either. After a while, someone that one of my tires was splitting. It turned out that I had it at 50 psi, the steel radials were exposed in the middle, and one side of the tire was larger than the other.

Maybe they were only rated for 32 PSI, like my Forester tires.

Someone on here figured out that wearing out the tires slightly faster was more than compensated by improved mileage, but I do not know that I would be able to find that thread now.

I obviously want high MPG 's. I want to pump up my tires a bit but not ruin them. What is considered a safe PSI increase without making the tires bald in the center as a result and not setting off the tire pressure monitoring system.

Factory specs: 32 PSI

On my 2011 Fiesta I ran sidewall max, 44 PSI, on the original tires (Kuhmo Solus) that came on the car new. At just over 30k miles, when I sold the car, the tires looked to me that they would easily do another 30k and there was no sign of any uneven tire wear. Thats 27k miles with no problem whatsoever.

I run the tires on my F-250 at 70 PSI. (sidewall max is 80) It rides like a wagon on dirt roads, but it handles quite well on smooth pavement. Can't tell if it's improved my fuel economy. I only drive it about 3K miles/year.
I've been running the tires on my Mustang @ 50 PSI (sidewall max is 51) for the last 3 months. It hasn't made a significant difference in MPG vs 40 PSI. (less than 0.06 MPG - 0.19% difference; and there was even less difference between 35 and 40 PSI) I'll be setting them at 35 PSI before I go to work Monday morning. A harsh ride isn't worth an improvement of less than 0.1 MPG.

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Fuel economy is nice, but sometimes I just gotta put the spurs to my pony!

Quote:

Originally Posted by thatguitarguy

Just 'cuz you can't do it, don't mean it can't be done...

Quote:

Originally Posted by elhigh

The presence of traffic is the single most complicating factor of hypermiling. I know what I'm going to do, it's contending with whatever the hell all these other people are going to do that makes things hard.

In my camaro I run recommended on all 4. It's more of a spirited driving car so I prefer some sidewall movement

In my wife's 2006 silverado 2500 4x4 we run 60 psi which is low for the 285/75/16 tires if I remember correctly. I have tried to over inflate them but the truck feels like its going to fall apart on rough roads because there is no sidewall cushion for all the weight of the chassis.

My first hx was running 45 psi on Douglas tires and felt like the silverado did, harsh ride on small bumps. These michelin defenders on my current hx ride amazing at 45psi and feel like I'm still driving on stock pressure.

When I first started reading here it was recommended no more than 10% over max psi, so that's usually what I go with